My 2000 lumen Dinotte has a very wide, very smooth beam. No hotspots. I run it at full power in the city, where there are bright car headlights and alternating brightly lit and dim areas of the streets. It's way too bright for dark country roads, I'll use the 25% 500 lumen setting at speeds less that 15-17 mph, click to brighter settings where my speed increases. Reflective road signs are blinding at 2000 lumens!
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Doubling the lumens makes the light "somewhat" brighter, not "twice as bright" to your eye.
I posted in
a 2018 thread:
The difference to your eye between 750 and 1000 is fairly subtle. The 750 should work.
Helmet mounts
I had a 200 (actual) lumen light, back when those were considered very bright. It was okay for riding under 15 mph, but gave very little warning at higher speeds. So I added an LED flashlight of 180 lumens on my helmet.
Advantages: seeing around a corner, very nice. Blasting a barking dog in the eyes, it backed off.
Disadvantages: I wanted to keep my head steady, so that the beam would normally point down the road. The narrow flashlight beam projected farther than the bike light. But that was hard on my neck! And in group rides, I had to be careful not to look at another rider.
Beam patterns
Some lights have a narrower beam that projects farther down the road for the same lumens. But these tend to have a sharper cutoff at the sides, which is kind of distracting to me.
I have a very bright light with a wide, smooth beam. So it lights up the whole width of the road, and the sides, too. I go full power in the city, to compete with car headlights and make a bright pool of light on the road. In the country, that's way too bright -- reflective signs are extremely bright.
Group rides at night
Like another post mentioned, bright lights behind a rider cast distracting, moving shadows in front of the rider. I put my light on the lowest setting, and aim it downwards. Each rider in a group just needs to light up the road directly in front of their wheel, then the whole group can see. So a light that can pivot downwards while riding is useful.
And the newest rear blinkies are way too bright for a group. Mine has a non-blink, dim mode.